Trihalosilane refining device

ABSTRACT

A trihalosilane refining device and a trihalosilane refining method are provided. The trihalosilane refining device can be useful in obtaining high-purity trihalosilane from a feed containing a trihalosilane while consuming a small amount of energy.

TECHNICAL FIELD

The present application relates to a trihalosilane refining device and atrihalosilane refining method.

BACKGROUND

Processes of preparing polycrystalline silicon which is a source ofmonocrystalline silicon may be mainly divided into a Siemens techniqueand a fluidized-bed reactor (FBR) technique. Here, polycrystallinesilicon produced through the Siemens technique accounts for 90% of thetotal output all over the world.

The Siemens technique includes a process using trichlorosilane as asource and a process using monosilane as a source. Here, the monosilanehas problems in that it is highly explosive, and a large amount ofby-products are produced during a manufacturing process. Therefore, atechnique using the trichlorosilane has been widely used in the relatedart.

Patent Document 1 discloses a method of refining trichlorosilane asdescribed above. However, methods disclosed in prior-art documentsincluding Patent Document 1 have problems in that an excessive amount ofenergy is consumed during production of products, and the producedproducts have a poor degree of purity.

Prior-Art Document

-   Patent Document 1: Japanese Patent Laid-open Publication No.    2002-234721

DESCRIPTION Technical Object

The present application is directed to providing a trihalosilanerefining device and a trihalosilane refining method.

Technical Solution

An illustrative trihalosilane refining device may include a divided walldistillation column (DWC) installed to enable an inflow of a feedcontaining a trihalosilane, and a first distillation column coupled tothe divided wall distillation column. The divided wall distillationcolumn may have at least one inlet port and at least three outlet portsformed therein. The divided wall distillation column of thetrihalosilane refining device may be designed so that the feed can beintroduced through the inlet port, and an effluent containing therefined trihalosilane can be extruded through one of the three outletports.

For example, the trihalosilane may be trichlorosilane. The trihalosilaneintroduced into the divided wall distillation column, for example,trichlorosilane, may be prepared using conventional methods known in therelated art. For example, trichlorosilane may be prepared by allowingmetallic silicon and hydrochloric acid, which is generally in a gasphase, to react at a high temperature, for example, approximately 300°C. to approximately 400° C. In addition to the trichlorosilane, areaction product containing the trichlorosilane prepared by theabove-described method includes hydrogen, unreacted hydrochloric acid,or a chlorosilane such as such as tetrachlorosilane or dichlorosilane.

The divided wall distillation column included in the trihalosilanerefining device is a so-called device designed to process a feedcontaining three components having a low boiling point, a middle boilingpoint and a high boiling point. The divided wall distillation column isa so-called device similar to a Petlyuk distillation column in athermodynamic aspect. The Petlyuk distillation column is designed tohave a structure in which a preliminary separator and a main separatorare thermally integrated so that a low boiling point material and a highboiling point material can be primarily separated at the preliminaryseparator, components present in upper and lower column portions of thepreliminary separator can flow into a feed plate of the main separator,and the low boiling point material, the middle boiling point materialand the high boiling point material can be finally separated at the mainseparator. In addition, the divided wall distillation column isconfigured with divided walls installed in the column so as to integratethe preliminary separator into the main separator.

FIG. 1 is a diagram showing a divided wall distillation column 100according to one illustrative embodiment. As shown in FIG. 1, thedistillation column 100 according to one illustrative embodiment mayhave a structure in which an inner part of the distillation column 100is divided by a divided wall 101 and which has a condenser 102 and areboiler 103 formed respectively in upper and lower portions thereof.The inner part of the divided wall distillation column 100 may beimaginarily divided by dotted lines shown in FIG. 1, for example,divided into an upper column region 104, a lower column region 105, apreliminary separation region 106, and a main separation region 107. Theterm “upper column region” refers to an upper region of the distillationcolumn 100 as schematically shown in FIG. 1, that is, a region 104 inwhich no divided wall is formed, and the term “lower column region”refers to a lower region of the distillation column 100 as schematicallyshown in FIG. 1, that is, a region 105 in which no divided wall isformed. Also, the term “preliminary separation region” may refer to aregion 106 in which an inlet port through which a feed F is supplied ispresent in spaces divided by the divided wall 101 as schematically shownin FIG. 1, and the term “main separation region” may refer to a region107 in which an outlet port through which an effluent EM flows out ispresent in the spaces divided by the divided wall 101 as schematicallyshown in FIG. 1. Typically, when the components in the feed F aredivided into a low boiling point component, a middle boiling pointcomponent and a high boiling point component, the low boiling pointcomponent and the high boiling point component may be mainly separatedat the preliminary separation region 106 of the divided walldistillation column 100, and a middle boiling point component may bemainly separated at the main separation region 107.

Unless expressly specified otherwise, the terms “low boiling pointcomponent,” “middle boiling point component” and “high boiling pointcomponent” may be used as relative concepts, for example, may refer tocomponents defined by dividing the respective components present in afeed into approximately three equal parts according to boiling points,or components flowing out respectively through first to third outletports, as will be described later, upon operation of the divided walldistillation column. In the case of the latter, the component (forexample, EU shown in FIG. 1) flowing out through the first outlet portmay be defined as a low boiling point component, the component (forexample, EM shown in FIG. 1) flowing out through the second outlet portmay be defined as a middle boiling point component, and the component(for example, ED shown in FIG. 3) flowing out through the third outletport may be defined as a high boiling point component.

As shown in FIG. 1, the divided wall distillation column of thetrihalosilane refining device may be formed with the upper and lowercolumn regions 104 and 105 open. In addition to the structure shown inFIG. 1, for example, the divided wall distillation column may have astructure in which the divided wall 101 shown in FIG. 1 extends to anupper portion of the distillation column with no open upper columnregion 104, or in which the divided wall 101 extends to a lower portionof the distillation column with no open upper column region 104according to a design. However, the divided wall distillation columnapplied to the trihalosilane refining device may desirably have astructure in which the upper and lower column regions are open, that is,a structure in which no divided wall is present in the upper columnregion of the distillation column and no divided wall is present in thelower column region of the distillation column either. According to sucha structure, it is possible to ensure a stream of a material (a liquidor a gas) between the preliminary separation region and the mainseparation region through the upper and lower column regions, therebyachieving excellent separation efficiency.

In the divided wall distillation column, an open length of the openupper and/or lower column region (that is, a length of a region in whichno divided wall is present in the upper column region, for example, adistance between a lower portion of the upper column region and an upperportion of the divided wall and/or a length of a region in which nodivided wall is present in the lower column region, for example, adistance between an upper portion of the lower column region and a lowerportion of the divided wall) may, for example, be in a range ofapproximately 800 mm to 3,500 mm, or approximately 1,200 mm to 2,500 mm.Within this length range, it is possible to ensure a smooth stream of amaterial between the preliminary separation region and the mainseparation region and maintain constant pressures in the preliminaryseparation region and the main separation region, thereby enhancingseparation efficiency, etc.

A plate number of the divided wall distillation column may, for example,be properly selected in consideration of the type of the distillationcolumn and desired separation efficiency. For example, when adistillation column having a packing type such as a structured packingtype is used in the divided wall distillation column, the plate numberof the distillation column may be the same as the theoretical platenumber. Also, a distillation column having a specific surface area ofapproximately 220 sqm/cum to 500 sqm/cum may be used as the distillationcolumn having such a packing type. When the specific surface area of thedistillation column is less than 220 sqm/cum, a significant increase intotal height of the distillation column may be caused. On the otherhand, when the specific surface area of the distillation column exceeds500 sqm/cum, streams of a liquid phase and a gas phase may not smoothlyoccur due to a decrease in internal pressure of the distillation column.

Also, when a distillation column having a tray type is used as thedivided wall distillation column, the distillation column may bedesigned to have a plate number so that separation efficiency can bemaintained at a level of approximately 50% to 80% with respect to thetheoretical plate number. When the distillation column is designed sothat the separation efficiency is maintained at a level less thanapproximately 50%, a low boiling point material and a high boiling pointmaterial may not be effectively separated at the preliminary separationregion, which results in degraded purity of a product. On the otherhand, when the distillation column is designed so that the separationefficiency exceeds 80%, it is difficult to maintain smooth equilibriumstreams between liquid and gas phases of a low boiling point materialand a middle boiling point material and liquid and gas phases of amiddle boiling point material and a high boiling point material, or theseparation efficiency may be deteriorated.

When the distillation column has a tray type, a gap between trays in adivided wall section of the distillation column, for example, a sectionindicated by the mark ‘DW’ shown in FIG. 1 may be selected within arange of approximately 200 mm to 1,500 mm. When the gap between thetrays is less than 200 mm, it is difficult to install, maintain and fixthe distillation column. On the other hand, when the gap between thetrays exceeds 1,500 mm, an increase in manufacturing cost may be caused.

Also, in the divided wall distillation column, the length of the dividedwall (for example, a length indicated by ‘DW’ shown in FIG. 1) may beadjusted according to compositions of a feed. For example, the length ofthe divided wall of the divided wall distillation column may bedetermined at a level of approximately 30% or more, or 40% or more withrespect to the total theoretical plate number. The term “totaltheoretical plate number” means a higher one of the sum of theoreticalplate numbers of the upper column region, the main separation region andthe lower column region of the divided wall distillation column, and thesum of theoretical plate numbers of the upper column region, thepreliminary separation region and the lower column region. As is knownin the related art, the theoretical plate number may be calculatedaccording to an equilibrium distillation curve for the compositions of acomponent present in the preliminary or main separation region.

When the length of the divided wall is less than 30% of the totaltheoretical plate number, proper separation is not performed at thepreliminary separation region, which results in degraded productionefficiency or degraded purity of a final product. An upper limit of thelength of the divided wall is not particularly limited, but may bedetermined without particular limitation as long as it can be set to avalue at which smooth flow of a material at the upper and lower columnregions is ensured. For example, the upper limit of the length of thedivided wall may be approximately 100%, 90% or less, 80% or less, or 70%or less with respect to the total theoretical plate number.

FIG. 2 is a graph illustrating a concentration profile oftrichlorosilane in the main separation region of the divided wallsection. The graph of FIG. 2 is shown for trichlorosilane refinedaccording to conditions described in Examples to be described later.Also, the concentration profile in which the length of the divided wallaccounts for 20%, 40% or 50% with respect to the total theoretical platenumber is shown in FIG. 2. In FIG. 2, the X axis represents a positionof the divided wall section in a length direction, and the Y axisrepresents a mass fraction of trichlorosilane in the position of thedivided wall section. When the length of the divided wall is less than30% of the total theoretical plate number as shown in FIG. 2, it can beseen that purity of a final product may be degraded due to a drasticdecrease in separation efficiency at the preliminary separation region.

The divided wall distillation column may include an inlet port and anoutlet port. For example, the distillation column may include one ormore inlet ports installed to introduce a feed into the preliminaryseparation region. Also, the distillation column may include at least afirst outlet port through which a component present at the upper columnregion may flow out, a second outlet port through which a componentpresent at the main separation region may flow out, and a third outletport through which a component present at the lower column region mayflow out. In the structure, a feed containing a trihalosilane isintroduced through the inlet port. Then, a low boiling point componentin the feed may flow out through the first outlet port, and a highboiling point component in the feed may flow out through the thirdoutlet port. The trihalosilane which is a target compound, for example,trichlorosilane, is typically included in a middle boiling pointcomponent. Therefore, in this structure, an effluent containing therefined trichlorosilane may flow out through the second outlet port.

According to one illustrative embodiment, the inlet port of the dividedwall distillation column may be installed to introduce the feed into thepreliminary separation region, and the inlet port may also be installedat a 1/10 to 9/10 section of the preliminary separation region. Theinlet port may, for example, be installed at a 1/10 to 8/10, 1/10 to7/10, 1/10 to 6/10, or 1/10 to 5/10 section of the preliminaryseparation region. The term “n/m section of a preliminary separationregion” may refer to a point spaced apart from the uppermost portion (anupper column region) of the preliminary separation region by n/m times alength of the preliminary separation region when the length of thepreliminary separation region is divided into m equal parts. Therefore,the term “ 1/10 to 9/10 section of a preliminary separation region” mayrefer to a section spanning from a point spaced apart from the uppermostportion (an upper column region) of the preliminary separation region by1/10 times the length of the preliminary separation region to a pointspaced apart from the uppermost portion of the preliminary separationregion by 9/10 times the length of the preliminary separation regionwhen the length (for example, a length indicated by ‘DW’ shown inFIG. 1) of the preliminary separation region is divided into 10 equalparts. When the feed is introduced into the preliminary separationregion as described above, a high boiling point material and a lowboiling point material may be properly separated at the preliminaryseparation region, thereby maintaining excellent purity and productionefficiency of a final product.

Also, the second outlet port may, for example, be formed at a 1/9 to 8/9section of the divided wall section of the main separation region. Thesecond outlet port may also be formed at a 2/9 to 8/9 section, a 3/9 to8/9 section, a 4/9 to 8/9 section, a 5/9 to 8/9 section, or a 6/9 to 8/9section of the divided wall section. The term “n/m section of a dividedwall section” may refer to a point spaced apart from the uppermostportion (an upper column region) of the main separation region or thedivided wall section by n/m times a length of the main separation regionor the divided wall section when the length of the main separationregion or the divided wall section is divided into m equal parts.Therefore, the term “ 1/9 to 8/9 section of a divided wall section” mayrefer to a section spanning from a point spaced apart from the uppermostportion (an upper column region) of the main separation region or thedivided wall section by 1/9 times the length of the main separationregion or the divided wall section to a point spaced apart from theuppermost portion of the main separation region or the divided wallsection by 8/9 times the length of the main separation region or thedivided wall section when the length (for example, a length indicated by‘DW’ shown in FIG. 1) of the main separation region or the divided wallsection is divided into 9 equal parts. As a result, a target materialsuch as trichlorosilane may be prevented from being mixed again with thehigh boiling point material or the low boiling point material at themain separation region, thereby maintaining excellent purity andproduction efficiency of a final product.

FIG. 3 is a graph illustrating a concentration profile oftrichlorosilane in the main separation region of the divided wallsection of the divided wall distillation column. The graph of FIG. 3 isshown for trichlorosilane refined according to methods described inExamples to be described later. In the graph of FIG. 3, the X axisrepresents a point of the divided wall section in a length direction(Top indicated on the X axis represents an end of the upper columnregion in the divided wall section, and Btm represents an end of thelower column region in the divided wall section.), and the Y axisrepresents a mass fraction of trichlorosilane. As shown in FIG. 3, whenthe divided wall section is formed out of position from the 1/9 to 8/9section, a mass fraction of trichlorosilane may be reduced. Therefore,when an outlet port is present in a section lower than the 1/9 section,a target compound may be mixed with the low boiling point material,which leads to degraded purity of the compound. On the other hand, whenan outlet port is present in a section higher than the 8/9 section, atarget compound may be mixed with the high boiling point material, whichalso leads to degraded purity of the compound.

When the feed containing the finely refined trihalosilane is introducedinto the divided wall distillation column, the feed may be separatedinto a low boiling point component and a high boiling point component atthe preliminary separation region. The low boiling point component andthe high boiling point component separated at the preliminary separationregion may refer to a component having a higher boiling point and acomponent having a lower boiling point, respectively, when therespective components of the feed are divided into approximately twoequal parts according to the boiling point. Some of the separated lowand high boiling point components flow in through the first outlet portof the upper column region and the third outlet port of the lower columnregion, respectively, and the remaining components flow in the mainseparation region, and then are distilled again. In this case, the lowand middle boiling point components may be mainly separated at an upperregion of the main separation region, and the middle and high boilingpoint components may be mainly separated at a lower region of the mainseparation region. After the low boiling point component separated thuspasses through the upper column region, the first outlet port and thecondenser, for example, some of the low boiling point component may flowout, or flow in an additional distillation column, and the remaining lowboiling point component may return to the upper column region by reflux.Also, after the separated high boiling point component passes throughthe lower column region, the third outlet port and the reboiler, some ofthe high boiling point component may flow out, or flow in an additionaldistillation column, and the remaining high boiling point component mayreturn to the lower column region by reflux.

As such, the second outlet port may, for example, be installed so that atemperature of the second outlet port or the component flowing outthrough the second outlet port, that is, a component containing atrihalosilane that is a target compound, can satisfy the followingExpression 1.

0.0132P ³−0.624P ²+12.673P+41.371≦Tm≦0.0132P ³−0.624P²+12.673P+51.371  Expression 1

In Expression 1, Tm represents a temperature of the second outlet portor the component flowing out through the second outlet port, and Prepresents an operating pressure of the upper column region of thedivided wall distillation column.

The respective components in the feed may be effectively separated byinstalling the second outlet port so as to satisfy Expression 1.

Meanwhile, in the divided wall distillation column, the first outletport may, for example, be installed so that a temperature of the firstoutlet port or the component flowing out through the first outlet portcan satisfy the following Expression 2.

0.0139P ³−0.6467P ²+12.692P+27.716≦Tt≦0.0139P ³−0.6467P²+12.692P+37.716  Expression 2

In Expression 2, Tt represents a temperature of the first outlet port orthe component flowing out through the first outlet port, and Prepresents an operating pressure of the upper column region of thedivided wall distillation column.

The respective components in the feed may be effectively separated byinstalling the first outlet port so as to satisfy Expression 2.

0.016P ³−0.7386P ²+14.3P+78.759≦Tb≦0.016P ³−0.7386P²+14.3P+88.759  Expression 3

In Expression 3, Tb represents a temperature of the third outlet port orthe component flowing out through the third outlet port, and Prepresents an operating pressure of the upper column region of thedivided wall distillation column.

The respective components in the feed may be effectively separated byinstalling the third outlet port so as to satisfy Expression 3.

In Expressions 1 to 3, specific ranges of P, Tt, Tb and/or Tm may beselected in consideration of process efficiency, etc. For example, theoperating pressure P of the upper column region may be set within arange of approximately 1.3 Kg/sqcmG to 23 Kg/sqcmG at an operatingtemperature in consideration of process efficiency, etc. Also, thetemperature Tt of the first outlet port or the component flowing outthrough the first outlet port may, for example, be in a range ofapproximately 72.2° C. to 102.2° C., or approximately 82.2° C. to 92.2°C. at a pressure of approximately 5.8 Kg/sqcmG, the temperature Tm ofthe second outlet port or the component flowing out through the secondoutlet port may be in a range of approximately 86.4° C. to 116.4° C., orapproximately 96.4° C. to 106.4° C. at a pressure of approximately 5.8Kg/sqcmG, and the temperature Tb of the third outlet port or thecomponent flowing out through the third outlet port may be in a range ofapproximately 129.9° C. to 159.9° C., or approximately 139.9° C. to149.9° C. at a pressure of approximately 5.8 Kg/sqcmG. In particular,when the temperature in each outlet port is adjusted within thistemperature range, energy required in the condenser or the reboiler maybe curtailed during a subsequent process, for example, a distillationprocess in the first distillation column coupled to the divided walldistillation column. The temperatures Tb, Tm and Tt may satisfy therelation of Tb>Tm>Tb. Also, the temperatures Tb, Tm and Tt applied toExpressions 1 to 3 represent temperatures of the respective outlet portsor the components flowing out through the outlet ports under an outflowpressure applied during operation of the divided wall distillationcolumn. As such, the temperature of the component flowing out througheach outlet port may also refers to a temperature of the component at apoint of time at which the component flows out through each outlet port,or a temperature of the component after the component flows out througheach outlet port, followed by going through the condenser or reboiler.Typically, the temperature of the component may refer to a temperatureafter the component flowing out through each outlet port goes throughthe condenser or reboiler.

The trihalosilane refining device may further include a firstdistillation column coupled to the divided wall distillation column. Forexample, the first distillation column may be coupled to the dividedwall distillation column to introduce the component flowing out throughthe second outlet port of the divided wall distillation column.Therefore, the trihalosilane flowing out from the divided walldistillation column may be further refined to obtain a desired productwith higher purity. As the first distillation column, a conventionaldistillation column known in the related art may be used withoutlimitation in consideration of separation efficiency, etc. Also, thetheoretical plate number, the operating temperature and the operatingpressure of the first distillation column are not particularly limitedeither, and may be properly selected in consideration of a feed to beintroduced. For example, the first distillation column may includeconventional distillation columns. Here, a distillation column having atheoretical plate number of approximately 20 to 100 or approximately 30to 60 may be used as the first distillation column. Also, the operatingpressure and the operating temperature of the distillation column may bein a range of approximately −0.6 Kg/sqcmG to 9.0 Kg/sqcmG, andapproximately 37° C. to 145° C., respectively. In particular, when thetemperature of the feed flowing out from the divided wall distillationcolumn and introduced into the first distillation column, for example,an outflow temperature through the second outlet port, is maintainedwithin this temperature range, energy consumed at the first distillationcolumn during the distillation process may be drastically curtailed.

Also, the trihalosilane refining device may further include a seconddistillation column configured to refine the component flowing out fromthe divided wall distillation column, for example, a high boiling pointcomponent. In this case, the second distillation column may be coupledto the divided wall distillation column to introduce the componentflowing out through the third outlet port of the divided walldistillation column. As necessary, among the components refined at thesecond distillation column, the high boiling point component, that is, acomponent flowing out from a lower portion of the second distillationcolumn, may be recycled and re-used as a source for preparing atrihalosilane. As the second distillation column, a conventionaldistillation column known in the related art may be used withoutparticular limitation in consideration of separation efficiency, etc.Also, the theoretical plate number, the operating temperature and theoperating pressure of the second distillation column are notparticularly limited, and may be properly selected in consideration of afeed to be introduced. For example, the second distillation column mayinclude conventional distillation columns. Here, a distillation columnhaving a theoretical plate number of approximately 20 to 100 orapproximately 30 to 60 may be used as the second distillation column.Also, the operating pressure and the operating temperature of thedistillation column may be in a range of approximately 0.1 Kg/sqcmG to52.5 Kg/sqcmG, and approximately 37° C. to 223.5° C., respectively. Inparticular, when the temperature of the feed flowing out from thedivided wall distillation column and introduced into the seconddistillation column, for example, an outflow temperature through thethird outlet port, is maintained within this temperature range, energyconsumed at the second distillation column during the distillationprocess may be drastically curtailed.

Also, the trihalosilane refining device may further include a thirddistillation column coupled to the first distillation column to enableinflow of an effluent flowing out from the first distillation column,for example, an effluent flowing out from a lower portion of the firstdistillation column. The trihalosilane may be further refined at thethird distillation column to obtain a target compound with higherpurity.

As the third distillation column, a conventional distillation columnknown in the related art may be used without particular limitation inconsideration of separation efficiency, etc. Also, the theoretical platenumber, the operating temperature and the operating pressure of thethird distillation column are not particularly limited, and may beproperly selected in consideration of a feed to be introduced. Forexample, the third distillation column may include conventionaldistillation columns. Here, a distillation column having a theoreticalplate number of approximately 5 to 60 or approximately 10 to 40 may beused as the third distillation column. Also, the operating pressure andthe operating temperature of the distillation column may be in a rangeof approximately 0.1 Kg/sqcmG to 50.5 Kg/sqcmG, and approximately 37° C.to 219.5° C., respectively.

Conventional distillation columns may be used as the first to thirddistillation columns. Each of the distillation columns may include aconventional condenser and reboiler. For example, a verticalthermosyphon having a natural circulation mode and a distillation columnhaving a forced circulation mode may be applied to inhibit fouling inthe distillation columns.

Another aspect of the present application provides a trihalosilanerefining method. The trihalosilane refining method according to oneillustrative embodiment of the present application may be performedusing the above-described trihalosilane refining device. For example,the trihalosilane refining method may include introducing a feedcontaining a trihalosilane into a divided wall distillation column(DWC), and introducing an effluent containing the trihalosilane flowingout from the divided wall distillation column into a first distillationcolumn coupled to the divided wall distillation column.

In this procedure, the distillation column as described above may beused as the divided wall distillation column. Also, the operatingconditions of the distillation column are not particularly limited. Forexample, the operating conditions of the distillation column may beadjusted within a range satisfying one, two or all of Expressions 1 to 3as described above, or may be adjusted within a range satisfying thespecific temperatures and pressures obtained from Expressions 1 to 3. Inthis procedure, the flow rate or temperature of the feed introduced intothe divided wall distillation column is not particularly limited. Forexample, the flow rate or temperature of the feed may be adjusted withina range satisfying one, two or all of Expressions 1 to 3 as describedabove, or may be adjusted within a range satisfying the specifictemperatures and pressures obtained from Expressions 1 to 3.

The trihalosilane refining method may include introducing an effluentflowing out from the divided wall distillation column, for example, aneffluent containing a trihalosilane, which flows out through the secondoutlet port, into the first distillation column. The distillation columnas described above may be used as the first distillation column. Asdescribed above, the trihalosilane flowing out from the divided walldistillation column may be further refined at the first distillationcolumn to obtain a target product with higher purity. The operatingconditions of the first distillation column are not particularlylimited. For example, the distillation column having a theoretical platenumber of approximately 20 to 100 or approximately 30 to 60 as describedabove may be used, and run so that the operating pressure and theoperating temperature can reach approximately −0.6 Kg/sqcmG to 9.0Kg/sqcmG, and approximately 37° C. to 145° C., respectively. In thisprocedure, when the temperature of the feed introduced into the firstdistillation column, for example, an outflow temperature through thesecond outlet port, is maintained within this temperature range, energyconsumed during the distillation process may be drastically curtailed.

Also, the trihalosilane refining method may further include introducingthe component flowing out from the divided wall distillation column, forexample, a component flowing out through the third outlet port presentin the lower column region, into the second distillation column. Thesame kind of distillation column as described above may be used as thesecond distillation column.

The operating conditions of the second distillation column are notparticularly limited. For example, a conventional distillation columnhaving a theoretical plate number of approximately 20 to 100 orapproximately 30 to 60 may be used, and run so that the operatingpressure and the operating temperature can reach approximately 0.1Kg/sqcmG to 52.5 Kg/sqcmG, and approximately 37° C. to 223.5° C.,respectively. When the temperature of the feed flowing out from dividedwall distillation column and introduced into the second distillationcolumn, for example, an outflow temperature through the third outletport, is maintained within this temperature range, energy consumed atthe distillation column during the distillation process may bedrastically curtailed.

Also, the trihalosilane refining method may further include introducingan effluent flowing out from the first distillation column, for example,an effluent flowing out from a lower portion of the first distillationcolumn, into the additional third distillation column. In this case, thetrihalosilane may be further refined at the third distillation column toobtain a target compound with higher purity.

The distillation column as described above may be used as the thirddistillation column. The operating conditions of the third distillationcolumn are not particularly limited. For example, a distillation columnhaving a theoretical plate number of approximately 5 to 60 orapproximately 10 to 40 may be used, and run so that an operatingpressure and an operating temperature can reach approximately 0.1Kg/sqcmG to 50.5 Kg/sqcmG, and approximately 37° C. to 219.5° C.,respectively.

Effect

According to the present application, the trihalosilane refining devicecan be useful in obtaining high-purity trihalosilane from a feedcontaining a trihalosilane while minimizing consumption of energy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a divided wall distillation column accordingto one illustrative embodiment;

FIGS. 2 and 3 are graphs illustrating a concentration profile oftrichlorosilane present in a divided wall section of a main separationregion of the divided wall distillation column;

FIG. 4 is a diagram showing a trihalosilane refining device used inExample 1; and

FIG. 5 is a diagram showing a trihalosilane refining device used inComparative Example 1.

BRIEF DESCRIPTION OF PARTS IN THE DRAWINGS

-   -   100 and 31: divided wall distillation column    -   101: divided wall    -   102: condenser    -   103: reboiler    -   104: upper column region    -   105: lower column region    -   106: preliminary separation region    -   107: main separation region    -   F: feed    -   EU, EM and ED: effluent    -   DW: divided wall section, preliminary or main separation region        or length thereof.    -   32 to 34: first to third distillation columns of Example 1    -   41 to 45: first to fifth distillation columns of Comparative        Example 1    -   A to K: respective streams in Example 1 or Comparative Example 1

ILLUSTRATIVE EMBODIMENTS

Hereinafter, the method will be described in detail referring toExamples and Comparative Examples; however the scope of the method isnot limited to the below description.

Example 1

A trihalosilane refining device having a structure shown in FIG. 4, forexample, a structure in which a divided wall distillation column 31, afirst distillation column 32, a second distillation column 33 and athird distillation column 34 were coupled to each another, was used toprepare a feed containing trichlorosilane using a conventional method.Then, a simulation was performed on a process of refining the feedcontaining the trichlorosilane. The simulation was performed using AspenPlus, and the conditions used for the simulation are listed in thefollowing Tables 1 and 2. In the process, a distillation column 31 inwhich a divided wall having a length of 50% with respect to the totaltheoretical plate number was installed was used as the divided walldistillation column 31. The feed introduced into the distillation column31 was introduced through the outlet port installed at a pointcorresponding to 3/10 of a length of the preliminary separation regionof the distillation column 31 from a top portion (an upper columnregion) of the preliminary separation region, and the effluentcontaining a trichlorosilane flowed out through the second outlet portinstalled at a point corresponding to 7/9 of a length of the dividedwall section of the distillation column 31 from a top portion (an uppercolumn region) of the divided wall section. Upon the simulation, anupper column pressure of the distillation column 31 was maintained atapproximately 5.8 Kg/sqcmG.

TABLE 1 Items of divided wall distillation column 31 Theoretical platenumber Upper column region 18 Preliminary separation region 38 Mainseparation region 38 Lower column region 20

TABLE 2 Second First distillation distillation Third distillation columncolumn column Theoretical plate number 45 40 24 Feed introduction plate29 5 13

The results obtained for respective streams (indicated by A to J in FIG.4) based on the simulation results are listed in the following Tables 3and 4 (For the respective streams, a temperature of stream C representsa temperature Tm of a component flowing out through the second outletport as applied to Expression 1, a temperature of stream B represents atemperature Tt of a component flowing out through the first outlet portas applied to Expression 2, and a temperature of stream D represents atemperature Tb of a component flowing out through the third outlet portas applied to Expression 3.).

TABLE 3 Stream No. A B C D E F G H I J Temperature 60.0 59.4 101.4 144.976.6 157.2 49.8 55.1 49.8 57.3 (° C.) Pressure 5.6 5.8 6.1 6.2 0.8 1.00.8 1.1 0.8 1.1 (Kg/sqcmG) Flow rate 1,909 22 1,640 247 190 57 30 1,6101,600 10 (Kg/hr) Mass fraction (%) HCl 0.26 22.561 0 0 0 0 0 0 0 0 DCS0.52 42.122 0 0 0 0 0 0 0 0 BCL3 0.01 0.868 0 0 0 0 0 0 0 0 TCS 86.2034.449 99.914 0.027 0.035 0 100 99.913 100 85.918 STC 10.00 0 0.08676.710 99.723 0 0 0.087 0 14.082 PCL3 0.01 0 0 0.077 0.1 0 0 0 0 0Heavies 3.0 0 0 23.186 0.142 100 0 0 0 0 HCl: hydrochloric acid DCS:dichlorosilane BCL3: boron trichloride TCS: trichlorosilane STC: silicontetrachloride PCL3: phosphorus trichloride Heavies: other high boilingpoint component

TABLE 4 Divided wall First Second Third distillation distillationdistillation distillation column column column column Calorie 2.3000.017 1.613 1.161 consumption (Gcal/hr)

Comparative Example 1

A trihalosilane refining device having a structure in which fiveconventional distillation columns were coupled to each another as shownin FIG. 5 was used to simulate a process of refining trichlorosilanepresent in the same feed as used in Example 1. The simulation wasperformed in the same Aspen Plus as used in Example 1. The conditionsused for the simulation are listed in the following Table 5.

TABLE 5 First Second Third Fourth Fifth distillation distillationdistillation distillation distillation column 41 column 42 column 43column 44 column 45 Theoretical 45 40 40 45 24 plate number Feed 13 1111 9 13 introduction plate

The results obtained for respective streams (indicated by A to K in FIG.5) based on the simulation results are listed in the following Tables 6and 7.

TABLE 6 Stream No. A B C D E F G H I J K Temperature 90.0 55.6 102.849.9 85.1 76.1 152.4 49.8 55.1 49.8 56.9 (° C.) Pressure 5.6 5.8 5.8 0.80.8 0.8 1.0 0.8 1.1 0.8 1.1 (Kg/sqcmG) Flow rate 1909 20 1889 1640 249190 59 30 1610 1600 10 (Kg/hr) Mass fraction (%) HCl 0.26 24.817 0 0 0 00 0 0 0 0 DCS 0.52 49.634 0 0 0 0 0 0 0 0 0 BCL3 0 0.954 0 0 0 0 0 0 0 00 TCS 86.2 24.595 86.852 99.93 0.719 0.942 0 99.99996 99.929 100 89.494STC 10 0 10.106 0.07 76.205 99.058 2.609 0.00004 0.071 0 11.056 PCL30.02 0 0.01 0 0.076 0 0.323 0 0 0 0 Heavies 3 0 3.032 0 23 0 97.068 0 00 0 HCl: hydrochloric acid DCS: dichlorosilane BCL3: boron trichlorideTCS: trichlorosilane STC: silicon tetrachloride PCL3: phosphorustrichloride Heavies: other high boiling point component

TABLE 7 First Second Third Fourth Fifth distillation distillationdistillation distillation distillation column 41 column 42 column 43column 44 column 45 Calorie 9.458 0.172 1.617 0.043 1.161 consumption(Gcal/hr)

As seen from the results, it was revealed that the energy (2.300Gcal/hr) consumed at the divided wall distillation column used inExample 1 was significantly lower than the energy (9.458 Gcal/hr+0.172Gcal/hr) consumed at the first and second distillation columns 41 and 42used in Comparative Example 1, which served as the divided walldistillation column used in Example 1. More particularly, it wasconfirmed that the energy was reduced by 7.330 Gcal/hr for an energycurtailment of approximately 76%. In comparison of the entire processes(the processes performed in the divided wall distillation column and thefirst to third distillation columns used in Example 1 versus theprocesses performed in the first to fifth distillation columns used inComparative Example 1), it could be seen that the energy was reduced byapproximately 7.36 Gcal/hr in Example 1 for an energy curtailment ofapproximately 59%, compared with Comparative Example 1.

1. A trihalosilane refining device comprising: a divided walldistillation column; and a first distillation column coupled to thedivided wall distillation column, wherein the divided wall distillationcolumn has an upper column region, a preliminary separation region, amain separation region and a lower column region formed therein, andcomprises: an inlet port installed to introduce a feed containing atrihalosilane into the preliminary separation region; a first outletport installed to enable outflow of a component in the upper columnregion and to satisfy the following Expression 2; a second outlet portinstalled to enable outflow of a component in the main separationregion; and a third outlet port installed to enable outflow of acomponent in the lower column region and to satisfy the followingExpression 3:0.0139P ³−0.6467P ²+12.692P+27.716≦Tt≦0.0139P ³−0.6467P²+12.692P+37.716  Expression 20.016P ³−0.7386P ²+14.3P+78.759≦Tb≦0.016P ³−0.7386P²+14.3P+88.759  Expression 3 wherein Tt represents a temperature of thefirst outlet port or the component flowing out through the first outletport, Tb represents a temperature of the third outlet port or thecomponent flowing out through the third outlet port, and P represents anoperating pressure of the upper column region of the divided walldistillation column.
 2. The trihalosilane refining device of claim 1,wherein the second outlet port is installed to satisfy the followingExpression 1:0.0132P ³−0.624P ²+12.673P+41.371≦Tm≦0.0132P ³−0.624P²+12.673P+51.371  Expression 1 wherein Tm represents a temperature ofthe second outlet port or the component flowing out through the secondoutlet port, and P represents an operating pressure of the upper columnregion of the divided wall distillation column.
 3. The trihalosilanerefining device of claim 1, wherein the operating pressure of the uppercolumn region is in a range of 1.3 to 23 Kg/sqcmG.
 4. The trihalosilanerefining device of claim 1, wherein a divided wall having a length of30% or more with respect to a total theoretical plate number is presentin the divided wall distillation column.
 5. The trihalosilane refiningdevice of claim 1, wherein the upper or lower column region has an openlength of 800 mm to 3,500 mm.
 6. The trihalosilane refining device ofclaim 1, wherein the inlet port is installed at a 1/10 to 9/10 sectionof the preliminary separation region to introduce the feed.
 7. Thetrihalosilane refining device of claim 1, wherein the second outlet portis formed at a 1/9 to 8/9 section of the divided wall section in themain separation region of the divided wall distillation column.
 8. Thetrihalosilane refining device of claim 1, wherein the first distillationcolumn is coupled to the divided wall distillation column to introduce acomponent flowing out through the second outlet port.
 9. Thetrihalosilane refining device of claim 1, further comprising: a seconddistillation column coupled to the divided wall distillation column tointroduce a component flowing out through the third outlet port.
 10. Thetrihalosilane refining device of claim 1, further comprising: a thirddistillation column installed to introduce a component flowing out froma lower portion of the first distillation column.
 11. A trihalosilanerefining method, comprising: supplying a feed containing a trihalosilaneinto a divided wall distillation column; and introducing an effluentflowing out from the divided wall distillation column into a firstdistillation column, wherein the divided wall distillation column has anupper column region, a preliminary separation region, a main separationregion and a lower column region formed therein, and comprises: an inletport installed to introduce a feed containing a trihalosilane into thepreliminary separation region; a first outlet port installed to enableoutflow of a component in the upper column region; a second outlet portinstalled to enable outflow of a component in the main separationregion; and a third outlet port installed to enable outflow of acomponent in the lower column region, and wherein operating conditionsof the divided wall distillation column are adjusted to satisfy thefollowing Expressions 2 and 3:0.0139P ³−0.6467P ²+12.692P+27.716≦Tt≦0.0139P ³−0.6467P²+12.692P+37.716  Expression 20.016P ³−0.7386P ²+14.3P+78.759≦Tb≦0.016P ³−0.7386P²+14.3P+88.759  Expression 3 wherein Tt represents a temperature of thefirst outlet port or the component flowing out through the first outletport, Tb represents a temperature of the third outlet port or thecomponent flowing out through the third outlet port, and P represents anoperating pressure of the upper column region of the divided walldistillation column.
 12. The trihalosilane refining device of claim 11,wherein the operating conditions of the divided wall distillation columnare adjusted to satisfy the following Expression 1:0.0132P ³−0.624P ²+12.673P+41.371≦Tm≦0.0132P ³−0.624P²+12.673P+51.371  Expression 1 wherein Tm represents a temperature ofthe second outlet port or the component flowing out through the secondoutlet port, and P represents an operating pressure of the upper columnregion of the divided wall distillation column.
 13. The trihalosilanerefining device of claim 11, wherein the upper column region ismaintained at an operating pressure of 1.3 to 23 Kg/sqcmG.
 14. Thetrihalosilane refining device of claim 11, wherein the feed isintroduced into the preliminary separation region through the inlet portinstalled at a 1/10 to 9/10 section of the preliminary separationregion.
 15. The trihalosilane refining device of claim 11, wherein thesecond outlet port is formed at a 1/9 to 8/9 section of the divided wallsection in the main separation region of the divided wall distillationcolumn, and the component flowing out through the second outlet port isintroduced into the first distillation column.
 16. The trihalosilanerefining device of claim 11, wherein the first distillation column ismaintained at an operating pressure of −0.6 Kg/sqcmG to 9.0 Kg/sqcmG andan operating temperature of 37° C. to 145° C.
 17. The trihalosilanerefining device of claim 11, further comprising: introducing thecomponent flowing out from the third outlet port into a seconddistillation column.
 18. The trihalosilane refining device of claim 17,wherein the second distillation column is maintained at an operatingpressure of 0.1 Kg/sqcmG to 52.5 Kg/sqcmG and an operating temperatureof 37° C. to 223.5° C.
 19. The trihalosilane refining device of claim11, further comprising: introducing an effluent flowing out from a lowerportion of the first distillation column into a third distillationcolumn.
 20. The trihalosilane refining method of claim 19, wherein thethird distillation column is maintained at an operating pressure of 0.1Kg/sqcmG to 50.5 Kg/sqcmG and an operating temperature of 37° C. to219.5° C.